Figure 1.

Metabolic pathways of NAA and NAAG. NAA is synthesized in neurons from aspartate and acetyl-CoA. It can then be exported to oligodendrocytes, where it is converted back to acetyl-CoA by aspartoacylase (an enzyme lost in Canavan's disease) and may thus be converted into lipids that form part of the myelin. Alternatively, it can be converted to NAAG in neurons and released to the extracellular space, where it is converted back to NAA by carboxypeptidases expressed on the extracellular surface of astrocytes.